I have brown discharge and I'm worried I'm pregnant.

Brown discharge is basically some old blood (like from your last period) that has gone dark mixed with your regular vaginal discharge. Usually, it happens after the period, but its not always the rule that it has to be after the period. It rarely has to do anything with pregnancy, so you don't have to worry about that if you were protected. Instead, it's more of the way your reproductive system is cleaning itself from the old cells and it's probably caused by small irritations to the inside of your vagina.